Fan



J n- 1, 1 w. .w. JOHNSTON 8 FAN Filed Aug. 5, 1933 2 Sheets-Sheet l ATTORNEYS.

Jan. 1, 1935.

w. w. JOHNSTON FAN Filed Aug. 5, 1933 2 Sheets-Sheet 2 INV NTOR.

ATTORNEYfi.

Patented Jan. 1, 1935 STA assignor of one-half to International Engineering, In'c. Da t n, Ohio, a corporation of Ohio A Application August 15, 1933, Serial N ...le83,ssi

I liclaimsi (o1. -:1 66) This invention relates to fans and,'in particu lar, to that type of :fanused for ventilation or cooling purposes. v

than the normal increase than at the center durdue merely to the increased linear speed at'the periphery."

. Another object is to rovide such a'fan wherein therateof increase intlievolume of airmo'ved is discontinuous, increasin'g gradually from the center outward-to a certain point and-then 'increasing suddenly by a large amount.

Another object is to provide such a fan where-' in the center portion moves air at a low rate where the motor obstructs the passage thereof,

and ate high rate atthe no suchobstruction. 4

Another object is to margin where there :is

provide such a fan having:

mainnancl' subsidiary blades which maybe cast in a single piece;

order that they may expend the minimum amount of power upon edge resistance 'lossesand the maximum amount in' moving theair.

' Another object is to provide such a "fan having.

all parts of the fan except the hub and ;-rim perform active air movingfunctions. I Another-object is to provide a fan which moves.

I a larger volume of air for" the space occu ied than. is moved by a fan having mainpropelling blades o l v blades to pass through .the air and consume a only.

Another'object' is to provide themaximuin-blade area at thepoint of maximum speed with the 1 least resistanceto'air movement seas to drive at high speed a cylinder of air in the-"areawhere there is the least resistance heeaiisefthere is no" impediment in the road of the-moton'etc.

removing the tips of the the air, such as driving blades in-this outer the air.

' In the'drawingsz I Figure I is a'front v iew of vention.

Figure 2 isan end view high speed area for moving thefari or myin or an outer subsidiary blade thereof, lookingin 'the direction "of the arrows'2 2 inFigure 1. L

Figure 3 is a crosssection through a main blade along the line 3-'3'of Figure 1. 3 Figure 4 is :a crossfisection through van inner subsidiary blade,- along the line .4-"4 in Figure l.

Figure 5-is a side elevation of the fan shown in Figure 1. g v

Figured is a. frontview of -a modified form of fan'having'main andlouter. subsidiary blades only. 10

Figure 7;i"sa.front viewof a modified formof fa'n having main andinner subsidiary blades only.

Referring to theidrawings in detail, the fair shown in Figure'l consists o'fi'a, hub 1 having a flanged portion 2 and a central portion 3 throughwhich passes the" shaft; bore 4 *provided with, the keyway 5; The drives-shaft, (not shown) ispro vided with a corresponding shit so that a key will engage the latter andthe keyway 5., thus fixedly attaching the fan to the drive shaft. The drive shaft is preferably rotated by an electric motor,

' which may be placed immediately behind the hub 1 and mounted upon astream lined cross mom-- ber behindthe fan. 5

Arranged radially outward from the hub 1 are the main fan blades 6 whichservenot only as air propellers but also as spokes toisu'pport a rim '7 connecting their peripheral ends: The rim '7 is of annular shape, and is-pi'ovidedrwith a plurality of subsidiary outer and inner fan blades 8 and 9 respectively.

ris sho'wnin Figures 2, 3land 4, the fan blades are of stream-lined or air-foil construction havingtheir entering edges bluht and their trail= ing edges sharp. This construction causes the fan minimumamount of power inthe edge resistance thereby: set, u -.-:--conse uent1y,. the maximumpart of the power consumed in driving. the fan goesinto 'the1useful work of'inoving'the air-for ventilation or cooling purposes; The fan blades are also preferably of helical or screw' construe-- tion, so thatthe a'iigleof inclination of the fan blade to the axis of rotation varies at differentpoints between -,the .tip and base of the fan blade. This screw construction .adds' to the efliciency of the fan blade.

The fan construction showmispreferably cast in "one piece. This one-piece construction adds to the-:strength of the fan, decreases thecostof manufacture, reduces the possibility of derange-,

ment. or breakdown during operation and enhances the appearanc'e since there are IlO'DOOketS or crevices formed, which might harbor dirt or grease. l 1

It will be seen from Figure 1 and from a consideration of the behavior of fan blades that the rate of air volume moved by the fan increases slowly as the point considered passes from the hub 1 to a circular line tangent to the tips 10 of the subsidiary blades 9. At this point, however, the subsidiary blades 9 add their propelling effect to that already created by the main blades 6, with the result that there isa suddenincrease in the rate of air volume moved by the fan at this point. The rate of air volume moved again in-' creases regularly as the point considered passes from the tips 10 of the inner subsidiary blade to the rim '7 and thence to the tips 11 of the'outer subsidiary blades 8. It will be seen, therefore, that in the central space immediatelysurrounding and in back of the hub 1, the rate of air volume moved is comparatively'lowfbut, as'this space is generally obstructed by the driving mo: tor, it would be inadvisable to provide a high rate of air propulsion therein. In the space outward from the tips 10 of the inner subsidiary blades 9, however,the motor obstruction is lacking, and consequently itis desirable to increase the propelling effect of the'fan'so that the volume of air moved thereby is. much larger for the space occupied by the fan than would bethe case ifthe main propelling blades 6 alone were used.

Themodified form of fanishown in Figure 6 is similar to the form shownin Figure 1, but possesses main blades 6 and outer subsidiary blades 8, the inner subsidiary-blades 9 being omitted. The modified form shown "in Figure"? is likewise similar to that of "Figure 1,'except that the fan has main blades 16 and inner subsidiary blades 9, the outer subsidiary blades 8 being omitted.

but the added effect of the outer subsidiary blades 81s, of course, lacking since these outer blades 8 themselves are absent.

While it is preferably to cast or otherwise make the fan blade of-my invention in a single piece, I

it is understood that it might be made in a plurality of pieces without departing from thescope or spirit of my invention.

It will be understood that I desire to comm.- hend within my invention such modificationsv as may be necessaryto adapt it to varying conditions and uses. m 1

Having thus .fully described my: invention, what I claim as newand desire to secure by Letters Patent'iisr 1 1. A fan comprising. a plurality of main blades;

a support carried by said main blades,f andsub' sidiary blades carried by said support, .thezentering edges of said blades being relatively bluntf compared with the trailing edges thereof.

2. A fan comprising aplurality of main blades,

a support carried by'said main blades, and sub-i sidiary blades carried by said supportysaid sub-' sidiary blades being directed radially fromsaid support, the entering edges of said blades'being relatively blunt comparedwith the trailingiedges thereof.

3. A fan comprising a hub, a plurality main.

blades attached to said hub, a support carried by said main blades near the tips thereof, and tapered subsidiary blades carried by said support, the entering edges of said blades being relatively blunt compared with the trailing edges thereof.

4. A fan comprising a main blade and a subsidiary bladev associated with-said main blade, the entering edges of said blades being relatively blunt compared with the trailing edges thereof,

whereby said blades are streamlined to reduce the edge resistance thereof.

5. A fan comprising a main blade and a subsidiary blade associated with said main blade, the-median planes of said blades having a variable angle with the axis of rotation thereof between said axis and the tips of said blades, the entering edges of said blades being relatively blunt compared with the trailing edges thereof.

6. A fan comprising a hub, a plurality of main blades attached to saidhub, a support carried by said-main blades near the tips thereof, and. subbeing. relatively blunt compared with the trailing edges thereof.

8.-In a fan, a hub and a plurality of major bladesradiating therefrom, an annular support bridging the ends of the said blades, and a-plurality of stub blades mounted thereon, the entering edges of said bladesbeing relatively blunt compared with the trailing edges thereof.

9. In a fan, a hub and a plurality of major blades radiating therefrom, an annular support bridging the ends of the said'blades, and a plurality of stub blades mounted thereon being greater in number'than themajor blades, the entering edges of said blades being relatively blunt compared with the trailingedges thereof.

10L In a fan, a huband a plurality of major blades-radiating therefrom, an annular support bridging the endsof thesaid blades, and a plurality of tapered supplementary stub blades mounted on the support and extending in opposite directions, said stub blades being greater in number than the major blades.

, 11.:In combination, a hub, a plurality of major fan blades, :and a plurality of oppositely disposed supplementary blades'lesser in length but greater :in number than the major blades, said supplementary blades being tapered.

12.In-combination, a hub, a plurality of major fan blades, and a plurality of oppositely disposed supplementary blades lesser in length but greater in numberv than the major blades, said supplementary blades being tapered toward their ends.

13. In combination, a fan, a hub, a plurality of major blades, a ring support mounted on the ends thereof, a plurality of radially disposed supplementary blades extending on the outside of, said'ring' outwardly, and a plurality of such blades extending on the inside of said ring inwardly, the total number; of said supplementary blades on either the outside or inside the ring being greater in number than the major blades, said outwardly extending supplementary blades having square ends and the inwardly extending blades having tapered ends.

14. In a fan, a hub, a plurality of relatively long major blades having their tips cut away, a ring mounted on the ends of said blades, and a plurality of inwardly extending tapered supplementary blades of lesser length than the major blades but greater in number.

WILLIAM W. JOHNSTON. 

